Alternatives to spruce in wooden aircraft construction?

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Joined
Nov 14, 2009
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8,413
Location
Rocky Mountains
Just finished the wood spread sheet for my AV-36 project. Weight gain using Ash is about 18# and a savings of $745 over Spruce from AS+S - not including packaging and shipping.

Now if I could find the same deal for 1mm thick ply...............
 

drdrainb

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Joined
May 9, 2016
Messages
10
Location
Lodi, CA, USA
Aircraft plywood seems like it will be around for a long time, if nothing else the Finnish birch type from sustainably managed forests, but spar quality spruce seems to be getting harder and harder to find. Yes, there are solutions like laminated spars, but at some point even that will be problematic. What if we want to keep building little airplanes largely of wood/plywood and fabric but without the spruce? I see at least four approaches, there are probably more:

1) Use other woods and take the weight penalty​
2) Build up plywood laminations into substitute spars, longerons, etc.​
3) Use hybrid plywood/aluminum construction with aluminum spars, longerons, etc. and plywood ribs, bulkheads, etc.​
4) Use selective composite reinforcement to give the required strength to an otherwise all-plywood design.​

Yes, I know that there are also the alternatives of going all-aluminum or all-composite, but let's keep this thread on topic for the "Wood Construction" section.

Cheers,

Matthew
except for- PORT ORFORD CEDAR. same weight for the same dimension, but slightly stronger. with the added BONUS that there is no need to varnish or seal this wood before covering, because of the natural oils contained in it- no dry rot. - so, a completed airframe will be slightly lighter and stronger than spruce.

so WHY did the army air core over look it? in the 30's, spruce was much more abundant than port orfard cedar- and? they didn't have epoxy & eurothane resins that would bond with cedar- typical wood glue of the day didn't work well with it. if you doubt orford's strength? - see the army air cores OWN study documentation of all the best candidates for aircraft wood.

the interesting thing about port orford cedar- is that it's actually in the cyprus family. if you're lucky enough to live within driving range of northern washington state- you can drive to a custom lumber supplier and buy it for a fraction of the cost of aircraft spruce. it will come in 3/4" siding, 5/4" decking & the typical 2 x 4 / 2 x 6 dimensional lumber- all vertical, clear grain- tight ring groups, very high qaulity. so you'll have to have use of a saw table to get it to the dimensions needed for your project- that is the easy part. if you have to have it shipped via freight, you'll end up paying about the same price as aircraft spruce: I checked. It might be possible to 'bundle' an order- if you find a fellow builder who's willing to split an order, then share freight cost- and reduce the overall cost per board foot.
 

Fiberglassworker

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Joined
May 28, 2021
Messages
88
Technical layer Beech or Birch, this is strips of veneer all laminated in the same direction.
It is quite a bit stronger than spruce so the sizes can be reduced quite a bit. Wicks lumber will custom fabricate this for you (At a price of course.) It was often used by the Scheibe aircraft company instead of spruce or fir for main spar construction.
 
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